The substrates suitable for refinish are either an old finish (production-line finish or repair finish), new parts which have been primed (mostly by electrodeposition, especially in the area of the finishing of heavy goods vehicle bodies), and also steel, aluminum, zinc plate or plastic. The choice of suitable coating materials and the process employed for the preparation of a refinish are determined by the surface to be finished and by the requirements of the customer.
A multicoat refinish is conventionally prepared by thorough cleaning of the damage site, sanding, treatment, if desired, with a surfacer and application of a repair filler to the area to be coated. In the case of all-over finishes, the entire old finish to be coated is pretreated analogously. Subsequently the area pretreated in this way is finished.
In this context, however, the preparation of metallic refinishes is a particular problem, because the color and brightness of the effect depend heavily on the manner of processing. Decisive factors at play here include the nozzle width of the spray gun and the spray pressure. The nature of dilution and the spray viscosity also influence color and effect. Especially when using aqueous basecoat compositions, clouding and similar effects are often observed.
The object of the present invention was therefore to provide a process for the preparation of a refinish having a very good quality, even in the case of critical colors. This means that changes in color, clouding and the like are to be avoided.